You know, I'm right there with you on the sacrilege part, but nowadays I microwave pasta all the time. You need to use a non-starchy pasta for this to work. I use plain store-bought Barilla Plus because I love it anyway. For fresh pasta, you could try a small experiment; I've never tried with freshly-made pasta.
It takes less time than boiling on the stove for me because I do this:
- Fill up the electric kettle with water and turn it on.
- I use a 1/2 gallon Pyrex measuring cup as my "pot", and I put an inch or so of water in that and pop it in the microwave for four minutes to warm it up.
- When the water's boiling in the kettle and the oven timer expires, I take out the Pyrex container, add the pasta and a little oil and some salt (optionally a little vinegar), and then pour in the boiling water to cover by an inch or so.
- Dumpling-like pasta (rotini or penne) take about 8:30 to cook on high (I've got I think an 1100 watt oven; experiment); spaghetti 5:30, thin spaghetti 4:30.
I know it sounds like a horrible sin, but I started doing it when I needed to cook small portions of pasta for my kids. I tried it myself, and realized that I could tell absolutely no difference from the results I got in my big pasta pot. When I need to boil a lot of pasta (like 2 14oz boxes) I still use the big pot of course, but a pound or less actually cooks up perfectly fine. My pasta cooker is enormous and takes a long time to come up to the boil.
Now once I tried this (not thinking clearly, obviously) with some very starchy, fancy pasta, and it did not work at all. But maybe because it's got so much extra protein, Barilla Plus comes out absolutely fine. (It's good for you too.)
edit — Here's an update: I still do this, but recently one of the seemingly endless succession of microwave ovens I've had recently died, and I'm pretty sure it's because it somewhat frequently overheated while doing this very thing (cooking pasta). Now I don't blame the technique, really, since an oven should probably be designed with the possibility of hot stuff being inside of them for some periods of time, but be warned. (It overheated probably 10 times or so over the course of a couple years before dying, so it was right about at what I find to be typical end-of-life anyway.)
Anything that breaks down due to heat is going to break down no matter HOW you cook it. Boiling only "destroys" nutrients by leaching them away into the water, which is the same reason that other people say that steaming/microwaving is better.
Thiamine, for example, is highly water soluble, so boiling is out. But it also breaks down at 100C, so you can't really cook it either. Niacin, on the other hand, leeches into water, but it's not heat-sensitive, so you can cook the hell out of it, as long as you don't get it wet. Folate is so fragile you can't leave your leafy greens in the sun without it breaking down (common with acids).
Basically, almost everything is better uncooked, but a lot of things are impossible to eat if you don't cook them enough to break down the cellulose. So eat a balanced diet, and stop worrying about the microwave.
Best Answer
I steam vegetables in large batches (up to 3 lbs) in covered Pyrex bowls in our large microwave. The microwave is 1800W, and steams the vegetables well in 4-6 minutes (depending on the vegetable...about 5 minutes for broccoli, which is fibrous). Bringing approximately 2" of water in an 8qt stockpot (the amount you'll likely need to heat in order to have the entire batch remain over steam before evaporating all the water)to a boil, plus steaming 3 lbs of broccoli in a steamer insert will take about 6 minutes on my stove on the 12,000BTU/hr gas burner.
So, that's 1800W x 5 min vs 12,000BTU/hr x 6 min
1W = 3.41BTU/hr
Converting the BTU/hr to watts that becomes
1800W x 5 min vs 3517W x 6 min
Since 1 W = 1Joule/second, the two energy expenditures are:
-Microwave: 1800J/s x 300s = 540,000 joules
-Stove: 3517 x 1,266,120 joules, more than twice the cost.
Stoves send a great deal of energy up the sides of the pans and into the air, where it is lost. Microwaves send nearly all their energy into the food. This means that in nearly every case, steaming in the microwave is more energy efficient.